'Nanoscoops' Could Cut EV Recharge Times

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'Nanoscoops' Could Cut EV Recharge Times

One drawback of electric vehicles, aside from range, is the time required to charge the battery. In most cases, you're looking at at least four to six hours if you're out of juice. Fashioning the electrodes out of a nanomaterial that looks a bit like an ice cream cone could dramatically reduce recharge times, making the technology more attractive.

Researchers at Rensselaer Polytechnic Institute have developed an electrode they claim can be charged and discharged at a rate 40 to 60 times faster than conventional battery anodes without sacrificing energy density. The team believes the technology could foster the development of high-power, high-capacity lithium ion batteries for everything from personal electronics to electric vehicles.

“Charging my laptop or cell phone in a few minutes, rather than an hour, sounds pretty good to me,” Nikhil Koratkar, a professor in the university's Department of Mechanical, Aerospace, and Nuclear Engineering, said in a statement. “By using our nanoscoops as the anode architecture for li-ion rechargeable batteries, this is a very real prospect. Moreover, this technology could potentially be ramped up to suit the demanding needs of batteries for electric automobiles.”

The nanoscoop material – so named because it resembles an ice cream cone – can withstand extremely high rates of charge and discharge that would cause conventional electrodes to rapidly deteriorate and fail.

In conventional li-ion batteries, the anode structure expands during charging and contracts while discharging. This stresses the anode. If the stress builds too quickly, the battery can fail prematurely. This is why batteries in most gadgets charge slowly.

The nanoscoop was engineered to withstand that stress. It features a carbon base with a thin layer of aluminum and a "scoop" of silicon (see image). The structures are flexible and can accept and discharge lithium ions at tremendous rates without significant damage. The nanoscoop is segemented, allowing the stress to be transferred from the carbon to the aluminum and then to the silicon. The gradual transition improves structural rigidity.

"Due to their nanoscale size, our nanoscoops can soak and release lithium at high rates far more effectively than the macroscale anodes used in today’s li-ion batteries," Koratkar said. "This means our nanoscoop may be the solution to a critical problem facing auto companies and other battery manufacturers – how can you increase the power density of a battery while still keeping the energy density high?"

There is one problem. The nanoscoop architecture is limited by the relatively low total mass of the electrode. Koratkar's team hopes to grow longer scoops with greater mass or find a way to stack layers of nanoscoops. Another possibility is growing nanoscoops on large flexible substrates that follow the contours of a vehicle's chassis.